Association of Star-Shaped Poly(d,l-lactide)s Containing Nucleobase Multiple Hydrogen Bonding

Abstract

A new family of associating polymers based on four-arm, star-shaped poly(D,L-lactide) (PDLLA) containing peripheral complementary hydrogen-bonding sites is described. Hydroxy-terminated, four-arm, star-shaped PDLLAs of controlled molar mass were functionalized with complementary DNA base pairs, adenine (A) and thymine (T), to obtain PDLLA-A and PDLLA-T, respectively. 1H NMR spectroscopy confirmed quantitative functionalization and the subsequent formation of PDLLA-A and PDLLA-T hydrogen-bonded complexes. Job's analysis revealed a 1:1 optimal stoichiometry for the hydrogen-bonded complexes, and the association constant (Ka) that was determined using the 1H NMR-based Benesi-Hildebrand treatment was 84 M(-1) for the low molar mass complementary polymers. Furthermore, the PDLLA-based hydrogen-bonded complexes exhibited higher solution viscosities compared to the corresponding non-hydrogen-bonded precursors, which further confirmed strong complementary multiple-hydrogen-bonding associations between the star-shaped polymers with terminal adenine and thymine groups. Moreover, variable-temperature 1H NMR studies demonstrated the thermoreversibility of the hydrogen-bonded PDLLA-based complexes in solution.

Supramolecular Biomaterials. A Modular Approach towards Tissue Engineering

“…63 Nucleobases were used as recognition motifs to functionalize low molecular weight prepolymers by the groups of Rowan 64,65 and Long. [66][67][68] Upon modification of the bisamino end-groups of telechelic PTHF with a molecular weight around 2 kg mol À1 with adenine-or cytosine-derivatives, respectively polymers 1 and 2, the material properties changed dramatically from a soft waxy solid to flexible materials with enough mechanical stability to be processed into fibers and films (Fig. 16).…”

“…Interestingly, they found strong associations between four-arm star-shaped adenine and thymine-containing poly(D,L-lactides). 68 Furthermore, the group of van Hest showed the synthesis of nucleobase-functionalized block copolymers via atom-transfer radical polymerization of thymine, adenine, cytosine, and guanine nucleobase-functional methacrylates. 69,70 The quadruple hydrogen-bonding UPy-unit, developed in our group, has been further employed in the functionalization of several low molecular weight polymers, such as poly-(dimethylsiloxanes) (PDMS), 41,71 poly(ethylene butylenes) (PEB), [72][73][74] poly(ethers), 72,75,76 poly(carbonates), 72,77 poly-(styrenes) (PS), 78 poly(isoprenes) (PI), 78 poly(ethylene-copropylenes) (PE-co-PP), 79 and poly(esters) 28,72,80,81 (Table 1).…”

Multi‐Responsive Supramolecular Double Hydrophilic Diblock Copolymer Driven by Host‐Guest Inclusion Complexation between β‐Cyclodextrin and Adamantyl Moieties

“…[13,14] The schizophrenic micellization behavior of linear PNIPAM-b-PDEA diblock copolymers has already been reported. [8,9,15] Recently, various types of non-covalent interactions, such as hydrogen bonding interactions, [16][17][18][19][20][21][22][23][24][25][26] metal-ligand interactions [27][28][29][30][31][32][33][34] and host-guest recognition [35][36][37] have been employed to construct supramolecular block or graft copolymers. [38] In the context of supramolecular chemistry, the hierarchical self-assembly of this novel type of block copolymers possesses unique characteristics.…”

Inhibitory effect of synthetic aromatic heterocycle thiosemicarbazone derivatives on mushroom tyrosinase: Insights from fluorescence, 1 H NMR titration and molecular docking studies

“…A 2.0 mL solution containing 5.0 lg/mL tyrosinase was added to the quartz cuvette, then titrated by successive addition of compound 1a, compound 1b, compound 1c and 1a-Cu 2+ complex (the constituent ratio of ligant and Cu 2+ was 1.5:1, the chelation ratio has been determined by continuous variation method) (Karikari, Mather, & Long, 2007) solution using a pipette (to final concentrations ranging from 0 to 60 lM). Fluorescence intensities were recorded using a Hitachi F-4600 spectrofluorophotometer (Japan) at three different temperatures (25, 30 and 35°C) with an excitation wavelength of 280 nm and excitation and emission slit widths of 5 nm.…”